Ventricular septal defect (VSD) is the most common form of congenital heart disease, so what are the main symptoms that babies with VSD often have and what are the basic tests that need to be done at the hospital? The symptoms of a small baby with VSD unfortunately depend on the size of the VSD fraction, which can simply be interpreted as the size of the VSD (of course size is only one of the main factors affecting the fraction), a small VSD may not have any symptoms and only a heart murmur will be detected during a routine check-up. With a large VSD, the baby will quickly show some symptoms: (1) easy sweating, shortness of breath, feeding difficulties; (2) repeated upper respiratory infections (“colds”) and even pneumonia; (3) delayed growth compared to small children of the same age; (4) limited exercise. If surgery is not performed in time, when the pressure of the pulmonary artery is close to the pressure of the aorta, the shunt flow will be reduced and the symptoms will be alleviated, but at this time, it means that the disease has become worse, and if there is further delay, the blood flow will be “reversed”, from left-to-right shunt to right-to-left shunt, and the patient will have purple lips and thick fingers (like a pestle and mortar). At this point, the patient will have end-stage heart disease, and surgery is no longer meaningful. So timely detection and appropriate timing for treatment is very important, so what tests should Baby with suspected VSD go to the hospital for? (1) Echocardiography, that is, ultrasound of the heart, so that a clear diagnosis can be made; (2) chest X-ray, which can determine how much pulmonary blood, such as end-stage heart disease, will show little pulmonary blood, pulmonary artery stump-like changes; (3) electrocardiogram, which can determine the right and left ventricular hypertrophy through the electrical axis, and then determine the progress of the disease; (4) cardiac catheterization, especially the right heart catheter, can determine the degree of pulmonary hypertension, especially (4) Cardiac catheterization, especially right heart catheterization, can determine the degree of pulmonary hypertension, especially when end-stage heart disease is suspected and the possibility of surgery is needed. As the most common congenital heart disease, although the surgical technique is relatively mature, cardiac surgery is still a surgery with risks, even the risk of death. Timely detection of Baby’s problem and timely visit to the relevant cardiac center to improve the examination is an important prerequisite for safe surgery.